[stable/horovod] Major version bump: Fix chart not being upgradable. (#8596)

See https://github.com/helm/charts/issues/7680.

Signed-off-by: Cédric de Saint Martin <cdesaintmartin@wiremind.fr>

stable/horovod/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v1
 description: A Helm chart for deploying Horovod
 name: horovod
-version: 0.2.1
+version: 1.0.0
 appVersion: 0.12.1
 sources:
   - https://github.com/uber/horovod

stable/horovod/README.md

@@ -8,7 +8,7 @@ This chart bootstraps Horovod which is a Distributed TensorFlow Framework on a K
 
 ## Prerequisites
 
-- Kubernetes cluster v1.8+ 
+- Kubernetes cluster v1.8+
 
 ## Build Docker Image
 
@@ -122,6 +122,21 @@ $ helm delete mnist
 The command removes all the Kubernetes components associated with the chart and
 deletes the release.
 
+## Upgrading an existing Release to a new major version
+A major chart version change (like v1.2.3 -> v2.0.0) indicates that there is an
+incompatible breaking change needing manual actions.
+
+### 1.0.0
+This version removes the `chart` label from the `spec.selector.matchLabels`
+which is immutable since `StatefulSet apps/v1beta2`. It has been inadvertently
+added, causing any subsequent upgrade to fail. See https://github.com/helm/charts/issues/7726.
+
+In order to upgrade, delete the Horovod StatefulSet before upgrading, supposing your Release is named `my-release`:
+
+```bash
+$ kubectl delete statefulsets.apps --cascade=false my-release
+```
+
 ## Configuration
 
 The following table lists the configurable parameters of the Horovod

stable/horovod/templates/statefulset.yaml

@@ -12,7 +12,6 @@ spec:
   selector:
     matchLabels:
       app: {{ template "horovod.name" . }}
-      chart: {{ template "horovod.chart" . }}
       release: {{ .Release.Name }}
       heritage: {{ .Release.Service }}
       role: worker
@@ -28,6 +27,11 @@ spec:
         heritage: {{ .Release.Service }}
         role: worker
     spec:
+      selector:
+        matchLabels:
+          app: {{ template "horovod.name" . }}
+          release: {{ .Release.Name }}
+          role: worker
       {{- if .Values.useHostNetwork }}
       hostNetwork: {{ .Values.useHostNetwork }}
       dnsPolicy: ClusterFirstWithHostNet
@@ -74,7 +78,7 @@ spec:
         - name: USESECRETS
           value: "{{ .Values.ssh.useSecrets }}"
        {{- end }}
-       {{- if .Values.master.env }}            
+       {{- if .Values.master.env }}
        {{- range $key, $value := .Values.master.env }}
         - name: "{{ $key }}"
           value: "{{ $value }}"
@@ -97,7 +101,7 @@ spec:
 {{- if .Values.volumeMounts }}
 {{ toYaml .Values.volumeMounts | indent 8 }}
 {{- end }}
-        command: 
+        command:
         - /horovod/generated/run.sh
 {{- if .Values.ssh.useSecrets }}
         readinessProbe: